1. Field of the Invention
The present invention relates to the construction and design of microwave multiplexers with contiguous or non-contiguous frequency channels and, in particular, to the construction and design of microwave multiplexers with channels exhibiting channel center frequencies that vary from one channel to the next in a monotonic fashion and exhibiting fractional bandwidths that vary from one channel to the next in a systematic, but otherwise arbitrary, user-defined manner. The present invention provides a non-logarithmic-periodic multiplexer which multiplexes/demultiplexes channels having various fractional bandwidths by use of one or more idealized infinite-array multiplexer prototypes for designing network segments which provide frequency selective filtering between individual composite-signal ports and associated channelized-signal ports.
2. Description of the Related Art
Presently, frequency multiplexers having channel fractional bandwidths which vary from one channel to the next are difficult to design and implement and generally require sophisticated computer-aided design tools. The prior art on constant-fractional-bandwidth multiplexers includes a logarithmic-periodic microwave multiplexer which can be efficiently designed and implemented as an array of logarithmic-periodically scaled substructures or segments. Logarithmic periodicity rigidly links circuit parameter values and characteristic frequencies defining a particular multiplexer segment to corresponding quantities of neighboring segments through a fixed logarithmic-periodic scaling factor. Accordingly, the logarithmic-periodic multiplexer of the prior art is made up of segments which share the same topology and which have circuit element values rigidly linked to one another from one channel segment to another channel segment through a fixed scaling factor. This basically confines independent design variables to those of a single segment and allows optimization of the entire logarithmic-periodic multiplexer by only requiring the optimization of one channel segment of the multiplexer. All other segments are merely frequency-scaled replicas of the one reference segment with their respective design parameters being implicitly determined by the reference segment parameters through the fixed frequency scaling factor.
What is needed is a non-logarithmic-periodic multiplexer which is more suitable than the prior-art logarithmic-periodic microwave multiplexer for multiplexing/demultiplexing contiguous or noncontiguous frequency channels whose fractional bandwidths are allowed to vary from one channel to the next in a systematic, but otherwise arbitrary, user-defined manner. In addition, what is also needed is a non-logarithmic-periodic multiplexer which limits the number of variables to be optimized to avoid dimensionality concerns that burden conventional optimization approaches for designing multiplexers. Further, what is needed is a non-logarithmic-periodic multiplexer whose array of channel segments may be arbitrarily expanded without materially degrading the performance of previously incorporated channels in the channel array.